The effect of heat soak on BMW M's turbo motors (S63TU), large power loss - F10 M5 back to back dyno pull testing by Evolve Automotive

BMW marketing has practically managed to convince people that their turbo motors are the greatest thing ever invented and a necessary evolution which will result in peace on earth and prosperity for all mankind. Fortunately, there are people out there who actually do real work and testing with these motors and what you are about to see is one of the downsides of the turbo generation. That would be the tremendous heat generated and power loss.

The new BMW M cars are not exactly light. The F10 M5 is heavy and it takes a good amount of turbo torque to get it moving. But that generates heat, a lot of it. Several wide open throttle pulls will result in what you see below which is horsepower going from 498.2 at the wheels to 443.2 for a loss of 50 wheel horsepower after seven WOT (wide open throttle) pulls.

On a hot day not only will one lose a lot of power after a few blasts but this is not a motor designed with the racetrack in mind. Yes, all motors suffer from heat soak, but the classic naturally aspirated motors do have an advantage in power retention and avoiding limp mode to the heat generated overwhelming the cooling system as they do not put out as much heat and do not requite as much cooling.

The odd thing about this is that the motors are supposed to be Motorsport derived. This is BMW M after all, isn't it? Well it's supposed to be but what this graph shows you is that the new M cars are more suited to quick wide open throttle blasts than sustained runs. That used to be AMG's game. Now it's BMW M's.

Out of curiosity, how conservative do you think it is? BMW rates the engine at 560 crank horsepower. 498 would be only a 12% drivetrain loss, which seems low. 443.2 from 560 would be a 20% drivetrain loss, which could be within reason for a conservative dyno. Maybe BMW does measure power output in a partial heat soak situation?

Ok amigos having a 335d I had the same issues I have pics of the OEM IC compared to the WAGNER IC, its just a simple plug and play and that my friends has made huge differance in how the car handles the hooter temps as we do here in Puerto Rico

i have the wagner IC too.
After 3 consecutive pulls my 335d already looses power on the dyno.
Its difficult to properly cool this turbo cars on a dyno.

My 335i use to lose a lot of power on back to back runs on pump gas no meth. I did a lot of datalogs to see what mods had effects on IAT and boost.
Intake, air scoops, FMIC, oil cooler upgrade, but man, on a 95F day coming from the beach on the highway, 3 back to back runs, I was basically getting beat by a stock G37... Then I knew turbo motors need meth.

Looks like the turbo idea holds true on all motors.. Man how I DONT miss those hot days where my 335i became a slug!

Between the turbos & air/water intercooling, the S63 is gonna hate repeated pulls. There's no way the OEM cooling system will be able to overcompensate for rising IATs/coolant temps once this car starts getting mods beyond simple tunes.

At least with air/air you can count on passive airflow & meth for immediate IAT reduction.

yes, you can get near to 320 crank hp investing some serious money. I would like to see if the new 4 cyl. turbo (tuned to 300 hp) does not suffer from heat on the dyno like the N52 did. Quiet impossible in my opinion.

I wonder if this is how BMW get the HP figures for their new turbo motors. Maybe they measure the HP after some heat soak and this is why we think they underate the engines but in reality they are what they say they are. We always see dynos with cool engines and try to make the conditions so we get the highest reading. What do you guys think?

You can clearly see the first cold run is not to be taken seriously at all. At this point the charge coolers do an excellent job at removing heat but cannot really do it for long.

If any of you have ever spent a few thousand miles in an F10 M5 like we have and you have a sensitive tuning butt dyno you will have noticed very much the drop off in performance doing continuous runs on the road. The first pull is always spectacular followed by good performance for a while and then it starts dropping off.

This is not actually that bad if you take away the first run.

If you think this is bad then you need to experience forced induction without any FMIC or Charge Cooler! Now that is horrendous!